Piezoelectric device and electronic apparatus

ABSTRACT

A piezoelectric device includes an insulating substrate, a piezoelectric vibration device that is mounted on a device mounting pad, a metal lid member that seals the piezoelectric vibration device in an airtight manner, an external pad that is arranged outside the insulating substrate, an oscillation circuit, a temperature compensation circuit, and a temperature sensor. The lid member and the temperature sensor or the lid member and the IC component are connected to each other so as to be heat-transferable, and a heat transfer member having thermal conductivity higher than that of the material of the insulating substrate is additionally included.

BACKGROUND

1. Technical Field

The present invention relates to a piezoelectric device, which is, forexample, acquired by mounting a temperature-sensor attached electroniccomponent outside a package of a piezoelectric vibrator, capable ofrealizing high-accuracy temperature characteristics including frequencydrift characteristics at the time of start-up by allowing the thermalstatus of the electronic component to approach that of the piezoelectricvibration device and an electronic apparatus having the piezoelectricdevice built therein.

2. Related Art

In the mobile communication market, the number of manufactures increaseswhich modularize a component group for each function in consideration ofmounting various electronic components, the maintenance and handlingthereof, and common characteristics of components between devices. Inaddition, a decrease in size and cost reduction are strongly demanded inaccordance with the modularization.

Particularly, the tendency of modularization becomes strong for circuitcomponents, of which the functions and the hardware configurations areset up and which requires high stability and high capability, such as anoscillation circuit used for generating a reference frequency signal, aPLL circuit, and a synthesizer circuit. Furthermore, by packaging such acomponent group as a module, there is an advantage that the shieldstructure can be easily set up.

As examples of a surface mounting-type IC component that is built bymodularizing and packaging a plurality of related components, there area piezoelectric vibrator, a piezoelectric oscillator, a SAW device, andthe like.

In JP-A-2006-191517, JP-A-2008-263564, and JP-A-2010-035078, surfacemounting-type piezoelectric oscillators are disclosed which have astructure in which an IC component including an oscillation circuit anda temperature compensation circuit is assembled outside a package of apiezoelectric vibrator for achieving further miniaturization while suchfunctions are maintained well.

In such a type of piezoelectric oscillator, a difference between thetemperature of a piezoelectric vibration device disposed inside thepiezoelectric vibrator and the temperature detected by the temperaturesensor mounted in the IC component that is connected to the outside ofthe piezoelectric vibrator may easily occur. Thus, in a case where thereis a temperature difference, the oscillation frequency of the oscillatoris corrected based on an output of the temperature sensor that is basedon incorrect temperature data. Accordingly, it is difficult to acquirestable temperature-frequency characteristics, and the frequency driftcharacteristics at the time of start-up deteriorate.

In order to respond to such an inconvenience, generally, a configurationhas been considered in which the temperature of the insulating substrateside, to which a piezoelectric vibrating reed is directly connected, isused as a measurement point.

In JP-A-2006-191517, a technology is disclosed in which thetemperature-frequency characteristics and the frequency driftcharacteristics are stabilized in a temperature-compensation typepiezoelectric oscillator in which an IC component as an oscillationcircuit device is connected to an electrode portion arranged outside apiezoelectric vibrator in which the piezoelectric vibrating reed ishoused inside the package by arranging a temperature sensor near theconnection terminal of the IC component connected to the electrodeportion so as to decrease the difference between the temperature of thepiezoelectric vibrating reed and the temperature detected by thetemperature sensor.

However, the connection terminal of the IC component that is connectedto the electrode portion of the piezoelectric vibrator side isconfigured so as to be conductive to an amplifier of the oscillationcircuit. In the amplifier, since heat is generated in accordance withthe operation thereof, when the temperature sensor approaches theelectrode portion of the piezoelectric vibrator side within the ICcomponent, the temperature of the heated IC component may be detected insome cases, and the above-described frequency drift characteristics maydeteriorate.

Next, in JP-A-2008-263564, a technology is disclosed in which thetemperature-frequency characteristics and the frequency driftcharacteristics are stabilized by decreasing a difference between thetemperature of a piezoelectric vibration device and the temperaturedetected by a temperature sensor by housing a first IC componentincluding an oscillation circuit and a temperature sensor inside apiezoelectric vibrator in which a piezoelectric vibration device ishoused inside a package, connecting a second IC component including atemperature compensation circuit to the outside of the piezoelectricvibrator and arranging the temperature sensor under the same temperatureenvironment as that of the piezoelectric vibration device.

However, a structure in which the IC component that may be originallyassembled outside the piezoelectric vibrator is divided into twocomponents, and the first IC component to which the temperature sensoris attached is housed inside the package has a low possibility ofimplementation in terms of cost-performance and blocks theminiaturization of the entire oscillator.

Next, in JP-A-2010-035078, a technology is disclosed in which thetemperature-frequency characteristics and the frequency driftcharacteristics are stabilized by decreasing a difference between thetemperature of a piezoelectric vibration device and the temperaturedetected by a temperature sensor by connecting an IC component to aconcave portion arranged outside a package housing the piezoelectricvibration device in a cantilever supporting state and connecting thetemperature sensor terminal of the IC component to a pillow memberarranged inside the package.

However, since a conductive adhesive is interposed between thepiezoelectric vibration device and a ceramic base of the package, thespeed of heat transfer to the piezoelectric vibration device is slowerthan the speed of heat transfer to the temperature sensor terminalthrough the pillow member. Accordingly, it is difficult to effectivelyimprove the frequency drift characteristics.

In any structure disclosed in the above-described technologies, thepiezoelectric vibration device is configured so as to be mounted in theceramic substrate (insulating substrate), and accordingly, it isunderstood that the temperature of the piezoelectric vibration devicecan be accurately detected by measuring the temperature of the ceramicsubstrate that is directly connected to the piezoelectric vibrationdevice to which a physical distance is short. However, actually, theeffect of further improving the frequency drift characteristics couldnot be sufficiently acquired.

As above, in a general surface mounting-type piezoelectric oscillator inwhich the IC component including a temperature sensor is connected tothe outside of the piezoelectric vibrator, there are problems in that adifference between the temperature of the piezoelectric vibration devicelocated inside the piezoelectric vibrator and the temperature detectedby the temperature sensor arranged outside the piezoelectric vibratormay easily occur, stable temperature-frequency characteristics cannot beacquired, and the frequency drift characteristics at the time ofstart-up deteriorate.

SUMMARY

An advantage of some aspects of the invention is that it provides asurface mounting-type piezoelectric oscillator, which is acquired bybuilding an IC component including a temperature sensor outside apackage of a piezoelectric vibrator, capable of realizing high-accuracytemperature characteristics including frequency drift characteristics atthe time of start-up by thermally connecting a metal lid member, whichis in a thermal status equivalent to that of the piezoelectric vibrationdevice due to its proximity to the piezoelectric vibration device, andthe IC component.

APPLICATION EXAMPLE 1

This application example of the invention is directed to a piezoelectricdevice including: an insulating substrate that includes a piezoelectricvibration device and a mounting terminal used for surface mounting; ametal lid member that is used for sealing the piezoelectric vibrationdevice between the insulating substrate and the lid member in anairtight manner, and an electronic component that includes at least atemperature sensor used for detecting temperature. The insulatingsubstrate includes an external pad that is an electrode and a heattransfer member that has thermal conductivity higher than that of aninsulating material of the insulating substrate and connects theexternal pad and the lid member, the electronic component is mounted inthe external pad, and the lid member and the temperature sensor areconnected so as to be heat-transferable through the external pad and theheat transfer member.

According to this application example, the lid member that is located ata position closest to the piezoelectric vibration device housed in anairtight space of the package and the temperature sensor or theelectronic component in which the temperature sensor is mounted arethermally connected to each other through the heat transfer memberhaving high thermal conductivity. Accordingly, incorrect temperaturedata is not output from the temperature sensor, whereby the frequencydrift characteristics can be improved.

APPLICATION EXAMPLE 2

This application example of the invention is directed to theabove-described piezoelectric device, wherein the heat transfer memberis made of metal and is electrically insulated from the mountingterminal.

According to this application example, since the heat transfer member isformed from an arbitrary metal material having thermal conductivityhigher than that of the material of the insulating substrate and iselectrically insulated from the mounting terminal, the temperaturesensor and the lid member or the like can be connected to each other soas to have high thermal conductivity.

APPLICATION EXAMPLE 3

This application example of the invention is directed to theabove-described piezoelectric device, wherein the electronic componentis a chip-shaped IC component in which the temperature sensor, atemperature compensation circuit, and an oscillation circuit used foramplifying an excitation signal of the piezoelectric vibration devicefor oscillation are formed as an integrated circuit.

Although, as examples of the electronic component, various componentscan be considered, as an example, there is the IC component.

APPLICATION EXAMPLE 4

This application example of the invention is directed to theabove-described piezoelectric device, wherein the electronic componentis a thermistor.

APPLICATION EXAMPLE 5

This application example of the invention is directed to theabove-described piezoelectric device, wherein the external pad connectedto the heat transfer member is connected to at least one of anadjustment terminal, a dummy terminal, and a temperature sensor terminalof the electronic component.

Such a neutral terminal can transfer the heat of the lid member to thetemperature sensor mounted in the IC component without being influencedby the heat of a main board.

APPLICATION EXAMPLE 6

This application example of the invention is directed to theabove-described piezoelectric device, wherein the insulating substrateis configured so as to include an upper concave portion used for housingthe piezoelectric vibration device on an upper face and includes a lowerconcave portion used for housing the electronic component on a lowerface, the external pad is included in the lower concave portion, and theheat transfer member is thermally connected to the electronic componentthrough the external pad that is arranged in the lower concave portion.

The insulating substrate, for example, may have a longitudinalcross-section shape of “H”.

APPLICATION EXAMPLE 7

This application example of the invention is directed to theabove-described piezoelectric device, wherein the insulating substrateincludes: a package unit that houses the piezoelectric vibration deviceon the inside thereof and includes a device housing concave portion ofwhich an upper opening is sealed by the lid member; and an electroniccomponent mounting unit that is drawn out from the package unit to theouter side and includes the external pad on the upper face, and the heattransfer member is thermally connected to the electronic componentthrough the external pad.

The invention can also be applied to an insulating substrate thatincludes the package unit and the IC component mounting unit that isdrawn out from the package unit to the outside.

APPLICATION EXAMPLE 8

This application example of the invention is directed to theabove-described piezoelectric device, wherein the external pad and themounting terminal are configured so as to be conductive to each other.

APPLICATION EXAMPLE 9

This application example of the invention is directed an electronicapparatus including any one of the piezoelectric devices according toApplication Examples 1 to 6.

The piezoelectric devices according to the application examples of theinvention can be applied to various electronic apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a longitudinal cross-sectional view of a crystal oscillator asan example of a surface mounting-type piezoelectric oscillator accordingto an embodiment of the invention.

FIG. 2 is a diagram showing the circuit configuration of the crystaloscillator shown in FIG. 1.

FIG. 3 is a cross-sectional view of a crystal oscillator according toanother embodiment of the invention.

FIG. 4 is a diagram showing the circuit configuration of the crystaloscillator shown in FIG. 3.

FIG. 5 is a cross-sectional view showing a device configuration in acase where the temperature of the crystal oscillator according to anembodiment of the invention is adjusted.

FIG. 6 is a longitudinal cross-sectional view showing the configurationof a crystal oscillator according to another embodiment of theinvention.

FIG. 7 is a longitudinal cross-sectional view showing the configurationof a crystal oscillator according to further another embodiment of theinvention.

FIG. 8 is the circuit configuration diagram of the crystal oscillatorshown in FIG. 7.

FIG. 9 is a diagram showing a cellular phone.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First, the inventors of the invention found that the temperature of apiezoelectric vibration device is closer to the temperature of a lidmember than that of an insulation container in which the piezoelectricvibration device is directly mounted.

Thus, in embodiments of the invention, the temperature of the lidmember, to be described later, is configured to be detected by using atemperature sensor to be described later for detecting the temperatureof the piezoelectric vibration device.

Hereinafter, embodiments of the invention that are illustrated in thedrawings will be described in detail.

FIG. 1 is a longitudinal cross-sectional view of a crystal oscillator asan example of a surface mounting-type piezoelectric oscillator as apiezoelectric device according to an embodiment of the invention. FIG. 2is a diagram showing the circuit configuration of the crystaloscillator.

The basic configuration of the crystal oscillator (piezoelectricoscillator) 1 according to the embodiment of the invention includes: aninsulating container (insulating substrate) 4 that has an internal pad(a device mounting pad) 5 electrically connected to each excitationelectrode of the crystal vibration device (piezoelectric vibrationdevice) 20 on the upper side and a plurality of mounting terminals 6 onthe lower side; the piezoelectric vibration device 20 that is mounted onthe internal pad 5 through a conductive adhesive 7; a metal lid member10 that seals the piezoelectric vibration device 20 in an airtightmanner together with the insulating container 4; an IC component 30 thatis mounted on an external pad (an IC component mounting pad) 12 arrangedin a portion of the insulating container located outside an airtightspace S in which the piezoelectric vibration device is housed and is anelectronic component that configures an oscillation circuit, atemperature compensation circuit, and a temperature sensor; a connectionconductor 9 that allows conduction between each mounting terminal 6,each internal pad 5, and each external pad 12; and a heat transfermember 15 that connects the lid member and the IC component so as to bethermally conductive and has thermal conductivity higher than that ofthe material of the insulating substrate.

In addition, it may be configured such that only a temperature sensorsuch as thermistor instead of the IC component 30 is mounted as anelectronic component so as to be connected to the external pad 12.

Next, the detailed configuration of the crystal oscillator(piezoelectric oscillator) 1 shown in FIG. 1 will be described.

The crystal oscillator 1 has a configuration in which the crystalvibration device (piezoelectric vibration device) 20 is mounted insidean upper concave portion 3 arranged on the upper face of a package 2 soas to be sealed in an airtight manner by the metal lid member 10, andthe IC component 30 is mounted on an outer bottom face (a lower concaveportion 11) of the package 2.

The package 2 includes: the insulating container (the insulatingsubstrate) 4 that is formed from an insulating material such as aceramic having the upper concave portion 3 on the upper face; twointernal pads (component mounting pads) that are arranged inside theupper concave portion 3 and are electrically connected to the respectiveexcitation electrodes of the crystal vibration device 20; a plurality ofmounting terminals 6 that are arranged on the outer bottom face of theinsulating container 4; the external pad (the IC component mounting pad)12 arranged inside the outer bottom face (the lower concave portion 11)of the insulating container that is used for mounting the IC component30 that includes the oscillation circuit, the temperature compensationcircuit, and the temperature sensor as an integrated circuit; theconnection conductor 9 that allows each mounting terminal 6, eachinternal pad 5, and the external pad 12 to be conductive to one another;the lid member 10 made of metal (for example, Kovar) that seals theupper concave portion 3 in an airtight manner in a state in which twointernal pads 5 disposed inside the upper concave portion 3 and twoexcitation electrodes disposed on the crystal vibration device(piezoelectric vibration device) 20 are electrically connected to eachother; and the heat transfer member 15 that connects the lid member andthe IC component so as to be heat-transferable and has thermalconductivity higher than the material of the insulating substrate thatis formed from a ceramic.

In this example, the insulating container (insulating substrate) 4 has alongitudinal cross-sectional shape of “H” in which the upper concaveportion 3 used for housing the piezoelectric vibration device 20 isarranged on the upper face, and the lower concave portion 11 used forhousing the IC component is arranged on the lower face.

The crystal vibration device 20 includes: a crystal substrate (forexample, an AT-cut crystal substrate) that is formed from apiezoelectric material such as crystal; the excitation electrodes thatare formed in vibration areas arranged on both faces including front andrear faces of the crystal substrate; lead electrodes that extend fromthe excitation electrodes to the end edge of the crystal substrate; andpads that are arranged in end portions of the lead terminals. Byconnecting the pads to the internal pads 5 using the conductive adhesive7, the crystal vibration device is mounted on the insulating container.

Each mounting terminal 6 is arranged on the bottom face of the lowerconcave portion 11 and, commonly, is configured by four mountingterminals including a driving power mounting terminal (Vcc terminal)that is conductive to lead electrodes arranged on the crystal vibrationdevice 20 side, a control voltage applying mounting terminal (Vconterminal), a signal-out mounting terminal (Out terminal), and a groundmounting terminal (Gnd) terminal that is used for being conductive to aground circuit.

In addition, the package 2 and the crystal vibration device 20 configurethe crystal vibrator (piezoelectric vibrator) 25.

The heat transfer member 15 is formed from molybdenum or an arbitrarymetal material having thermal conductivity higher than that of thematerial of the insulating substrate. One end portion (an end portionconnected to the lid member) of the heat transfer member 15 is thermallyconnected to the lid member 10, and the other end portion (an endportion connected to the IC component) thereof is thermally connected toan appropriate portion on the outer face of the IC component 30 of asilicon bare chip, whereby the heat transferred from the lid member 10is conductive to the IC component 30 so as to allow the temperature ofat least the lid member 10 (the crystal vibration device 20) and anappropriate portion on the outer face of the IC component 30 or thetemperature of a range including the periphery thereof to be equal in aspeedy manner and be equivalently maintained. The lid member is made ofa metal material having thermal conductivity higher than that of theinsulating substrate, and is located proximal to the crystal vibrationdevice 20 disposed inside the upper concave portion 3, whereby the lidmember and the crystal vibration device 20 are at equivalenttemperatures. Accordingly, by thermally combining the lid member 10 andthe IC component by using the heat transfer member 15 having highthermal conductivity, the temperature of the IC component canunlimitedly approach the temperature of the crystal vibration device 20.

In a case where the heat transfer member 15 is wired within thethickness of the insulating container 4, when the insulating containeris formed by laminating ceramic sheets, a through hole is formed in aportion of the heat transfer member corresponding to a wiring path, anda metal material is filled (metalized) in the through hole. On the otherhand, in a case where a part of the heat transfer member is wired on theouter face of the insulating container, the metal material is metalizedat the portion.

The IC component 30 is an IC chip as a bare chip that includesintegrated circuits such as an oscillation circuit (an amplifier circuitthat is used for amplifying an excitation signal of the piezoelectricvibration device for the use of oscillation) and a temperaturecompensation circuit (a circuit that is used for compensating thefrequency-temperature characteristics of the piezoelectric vibrationdevice), and a temperature sensor (temperature-sensitive device) isbuilt therein.

By connecting each terminal that is arranged so as to be exposed to theouter face of the IC component to the IC component mounting pad 12through a metal bump formed from gold or the like or soldering in theone-to-one correspondence state, the IC component 30 is fixed to thelower concave portion.

Since the IC component 30 as a bare chip made from silicon has overalluniform and good thermal conductivity, the other end portion of the heattransfer member 15 may be brought into contact with (connected to) anyportion of the outer face of the IC component. However, it is preferablethat the other end portion of the heat transfer member 15 is broughtinto contact with a portion that is located near the temperature sensor.More specifically, for example, it is preferable that the other endportion is mechanically and thermally connected to a terminal (a neutralterminal), which is not electrically connected to a main board MB inwhich the crystal oscillator 1 is mounted, of terminals arranged on theouter face of the IC component through a metal connection medium such asa metal bump.

The reason for this is that a terminal that is electrically connected tothe main board MB is configured so as to be conductive to the mountingterminal used for surface mounting.

In the surface mounting, the mounting terminal is brought into surfacecontact with the main board MB, and accordingly, heat can be easilydelivered from the main board MB to the piezoelectric device.

Accordingly, by using a neutral terminal, as described above, astructure is formed in which heat from the lid member can be transferredmore easily than heat (temperature) from members other than the lidmember 10, which is transferred from the main board MB, to thetemperature sensor. Accordingly, the temperature sensor detects thetemperature under thermal conditions that are equivalent to those of thecrystal vibration device, and the temperature compensation circuit isoperated based on the temperature data, whereby the frequency can becontrolled with high accuracy.

As examples of the neutral terminal in this embodiment, there are anadjustment terminal that is arranged so as to be exposed to the outerface of the IC component, an NC (non-connect) terminal, a dummyterminal, and the like. Preferably, the neutral terminal is a terminalthat is not electrically conductive to the mounting terminal of the mainboard MB.

By connecting at least one of such terminals and the other end portionof the heat transfer member to each other, it is possible to resolve atemperature difference between the crystal vibration device and the ICcomponent.

The adjustment terminal is disposed for measuring and adjusting thecharacteristics of the IC component at the time of manufacturing, is notused after the end of the adjustment and the completion of theoscillator, and is not connected to the main board MB. Accordingly, theadjustment terminal can be used for a connection with the lid member.

While the adjustment terminal is conductive to a probe for inputtingdata to the IC component or outputting data from the IC component, theNC terminal or the dummy terminal does not perform such input or outputof data.

Thus, when a temperature change due to a contact with the probe in suchan adjustment process is concerned about, it is preferable that the heattransfer member is connected to the NC terminal or the dummy terminal.

As shown in the circuit diagram shown in FIG. 2, in the IC component 30that is externally attached to the crystal vibrator 25 that includes thecrystal vibration device 20, an oscillation circuit 31, a temperaturecompensation circuit 33, a temperature sensor (thermistor) 40, an A/Dconverter 35, and the like are mounted. The output (temperatureinformation) of the temperature sensor 40 is formed as a digital signalby the A/D converter 35, and the digital signal is input to thetemperature compensation circuit 33. The temperature compensationcircuit 33 outputs frequency control information generated based on thetemperature information to the oscillation circuit 31. The oscillationcircuit 31 outputs temperature compensation frequency information basedon the temperature control information.

A terminal 42 shown in FIG. 2 is a neutral terminal that has thefunctions of an adjustment terminal, an NC (non-connect) terminal, and adummy terminal.

Although an NC terminal that is not shown in the figure is a terminalthat is originally used for inputting a DC voltage for frequencyadjustment, it is used for a connection with the lid member in a casewhere the function thereof as the piezoelectric device is not necessary.

The dummy terminal is a terminal dedicated for heat transfer that doesnot have a special use other than a thermal connection between the lidmember 10 and the IC component through a connection with the heattransfer member.

The heat transfer member 15, as shown in the figure, may be disposedwithin the thickness of the insulating substrate that is interposedbetween the lid member and the IC component, or the heat transfer member15 may be disposed in a state in which a part of the heat transfermember is exposed to an outer portion (including a concave portion innerwall) of the insulating substrate.

As shown in FIG. 1, on an upper end face of the insulating container 4,a metal sealing body such as a seam ring 8 is formed as a sealing membermade of metal used for welding the lid member 10. When the insulatingcontainer is manufactured, one end portion of the heat transfer member15 is in a state of being in contact (welded) with the seam ring 8. Whenthe lid member is welded together with the seam ring, one end portion ofthe heat transfer member is connected to the lid member so as to befixed. A middle portion of the heat transfer member 15 is disposedwithin the thickness of the insulating container or along the outerface, and the other end portion thereof extends to the inner bottom faceof the lower concave portion 11 and is connected to the external pad 12that is fixed to the terminal 36 of the IC component that is thermallyneutral.

In such a configuration, the lid member and the terminal 36 areconnected to each other through metal, and accordingly, a structurehaving high thermal conductivity is formed.

In order to improve the frequency drift characteristics by allowing thetemperature data acquired by the temperature sensor 40 mounted in the ICcomponent 30 to approach the temperature of the crystal vibration device20 when the crystal oscillator 1 is started up, it is effective toincrease the amount of heat to be transferred to the IC component by theheat transfer member 15 as much as possible. Accordingly, although it iseffective to increase the diameter of the heat transfer member, there isa limitation on the increase in the diameter in relation with the platethickness of the insulating substrate, and accordingly, it ispractically effective to increase the number of the heat transfermembers. In a case where the number of the heat transfer members isincreased, the heat transfer members are arranged in the facialdirection of the insulating substrate (a direction perpendicular to thethickness direction of the plate).

In a case where a plurality of the heat transfer members is disposed, itmay be configured such that, to an appropriate portion of a heattransfer member as a base, the other end portions of the other heattransfer members are connected, and the end portions connected to the ICcomponent are integrally formed. Alternatively, it may be configuredsuch that the connection terminal portion of each heat transfer memberis individually connected to the IC component.

FIG. 3 is a cross-sectional view of a crystal oscillator according toanother embodiment of the invention, and the same reference numeral isassigned to the same member as that shown in FIG. 1 for the description.FIG. 4 is a diagram showing the circuit configuration of this crystaloscillator.

A difference between the crystal oscillator 1 according to thisembodiment and the crystal oscillator 1 according to the embodimentshown in FIG. 1 is that the neutral terminal to which the other endportion of the heat transfer member 15 is connected is configured as atemperature sensor terminal 45 that is arranged so as to be exposed tothe outer face of the IC component 30 in this embodiment.

As shown in FIG. 4, the temperature sensor terminal is a terminal thatis electrically connected to the temperature sensor (thermistor) 40 andis, for example, a terminal of the temperature sensor that is used foroutputting the temperature information. By exposing the temperaturesensor terminal 45 to the outer face of the IC component, thetemperature sensor terminal 45 is thermally connected to the other endportion of the heat transfer member 15. The temperature sensor terminal45 is preferably a terminal that is not conductively connected to themain board MB and is further connected to the temperature sensor 40through a metal wiring arranged on the silicon substrate. Accordingly,by connecting the temperature sensor terminal 45 to the lid member 10,heat from the lid member can be easily transferred to the temperaturesensor 40, whereby the sensitivity of the temperature sensor fordetecting the temperature of the piezoelectric vibration device can beimproved.

Differently from the embodiments described with reference to FIGS. 1 and2, a neutral terminal that is not thermally and electrically connectedto the main board MB in which the crystal oscillator 1 is mounted, thatis, preferably a terminal that is not electrically conductive to themounting terminal of the main board MB may be connected to the lidmember 10 through the heat transfer member.

Alternatively, it may be configured such that the area of the other endportion of the heat transfer member 15 is broadened so as to be broughtinto contact with the outer face (a face other than the terminal formingportion) of the IC component in a broad area, whereby the amount of heattransferred from the lid member to the IC component is increased.

FIG. 5 is a cross-sectional view showing a device configuration in acase where the temperature of the crystal oscillator according to anembodiment of the invention is adjusted.

When the temperature adjustment is performed, the crystal oscillator 1is placed in a state in which the outer face of the lid member 10 isbrought into facial contact with a flat face of a stage 50 that isheated by a heating unit such as a Peltier device, and the temperatureis adjusted while operating the oscillator in a state in which a probe52 is brought into contact with an external terminal that is arranged onthe bottom face of the insulating container 4.

In a case where a temperature adjustment operation is performed for ageneral crystal oscillator in which the heat transfer member 15 is notincluded by a temperature adjusting device, the heat of the insulatingcontainer is absorbed by the probe 52 that is in contact with theexternal terminal, and accordingly, there is a deviation between thetemperature of the IC component 30 and the temperature of the crystalvibration device 20. In other words, in a general crystal oscillator,the IC component 30 is mounted on the bottom face of the lower concaveportion 11, and accordingly, the temperature sensor located inside theIC component detects the temperature of the bottom face of the lowerconcave portion. Accordingly, as the temperature of the bottom face ofthe lower concave portion is absorbed by the probe, there is aconsiderable temperature difference between the crystal vibration device20 housed in the upper concave portion 3 and the IC component, wherebyit is difficult to accurately perform temperature adjustment.

In contrast to this, in a case where temperature adjustment is performedfor the crystal oscillator according to each embodiment of theinvention, not the temperature of the bottom face of the lower concaveportion but the temperature of the lid member 10 brought into contactwith the stage 50 is detected by the temperature sensor mounted in theIC component. Accordingly, the temperature difference between thecrystal vibration device 20 and the IC component 30 decreases, wherebythe accuracy of the temperature adjustment can be improved.

Particularly, in the crystal oscillator according to the embodimentshown in FIG. 3, the temperature sensor terminal 45 is directlyconnected to the lid member 10. Accordingly, the temperature of the lidmember can be measured more directly, whereby the temperature differenceof both parties further decreases. Therefore, the adjustment can beperformed with higher accuracy.

As above, according to the embodiment of the invention, the temperaturedetected by the temperature sensor reliably reflects the temperature ofthe crystal vibration device, whereby the crystal vibration device andthe IC component (at least the temperature sensor) are operated based onthe same temperature.

FIG. 6 is a longitudinal cross-sectional view showing the configurationof a crystal oscillator (piezoelectric oscillator) according to anotherembodiment of the invention. The same reference numeral is assigned tothe same portion as that shown in FIG. 1 for the description.

An insulating container (insulating substrate) 4 that configures thiscrystal oscillator 1 includes a package unit that houses a crystalvibration device (piezoelectric vibration device) 20 on the insidethereof and includes a device housing concave portion 3 of which anupper opening is sealed by a lid member 10 and an IC component mountingunit 70 that is drawn out from the package unit to the outer side (thelateral side in this example) and includes an IC component mounting pad(external pad) 71 on the upper face thereof.

The crystal oscillator 1 has a configuration in which a crystal vibrator60 is configured so as to be sealed by the lid member 10 in a state inwhich the crystal vibration device 20 is housed in the device housingconcave portion 3, and an IC component 30 that includes an oscillationcircuit, a temperature compensation circuit, and a temperature sensorare connected to the IC component mounting pad 71 through a metal bumpor soldering.

A featured configuration of this embodiment is that, by thermallyconnecting the IC component 30 and the lid member 10 through a heattransfer member 15 arranged on the inside or the outer face of theinsulating container (package unit) 4, the temperature of the ICcomponent is uniformized with the temperature of the crystal vibrationdevice 20 that is located near the lid member.

More specifically, similarly to the above-described embodiment, bymetalizing the heat transfer member 15, a structure is formed in which aterminal 36 of the IC component 30 and the lid member 10 are connectedto each other through a heat transfer path made of metal.

One end portion of the heat transfer member 15 is connected to the lidmember 10, and the other end portion thereof may be brought into contactwith any portion of the outer face of the IC component of the heattransfer member 15. However, it is preferable that the other end portionof the heat transfer member 15 is brought into contact with a portion ofthe IC component that is located near the temperature sensor. Morespecifically, for example, the other end portion is mechanically andthermally connected to a terminal (a neutral terminal) 36, which is notelectrically connected to a main board MB in which the crystaloscillator 1 is mounted, of terminals arranged on the outer face of theIC component through a metal connection medium such as a metal bump.Accordingly, a structure is formed in which heat from the lid member canbe transferred more easily than heat (temperature) from members otherthan the lid member 10, which is transferred from the main board MB, tothe temperature sensor. Accordingly, the temperature sensor detects thetemperature under thermal conditions that are equivalent to those of thecrystal vibration device, and the temperature compensation circuit isoperated based on the temperature data, whereby the frequency can becontrolled with high accuracy.

As examples of the neutral terminal 36 that is thermally neutral, thereare an adjustment terminal that is arranged so as to be exposed to theouter face of the IC component, a temperature sensor terminal, an NC(non-connect) terminal, a dummy terminal, and the like. By connecting atleast one of such terminals and the other end portion of the heattransfer member to each other, it is possible to resolve a temperaturedifference between the crystal vibration device and the IC component.Accordingly, the frequency drift characteristics can be improved.

FIG. 7 is a longitudinal cross-sectional view showing the configurationof a crystal vibrator (piezoelectric vibrator) according to furtheranother embodiment of the invention. FIG. 8 is the circuit configurationdiagram of a crystal oscillator (piezoelectric oscillator) that isconfigured by the piezoelectric vibrator. The same reference numeral isassigned to the same portion as that of the embodiment shown in FIG. 1for the description.

The crystal vibrator A is a temperature sensor-attached crystal vibrator(piezoelectric vibrator) that includes: a package 2 having across-section shape of “H”; a crystal vibration device (piezoelectricvibration device) 20 that is housed inside an upper concave portion 3disposed on the upper face of the package 2; a metal lid member 10 thatseals the upper concave portion 3 in an airtight manner; and atemperature sensor (temperature-sensitive device) 80 as an electroniccomponent such as a thermistor mounted on the outer bottom face (a lowerconcave portion 11) of the package 2.

The crystal oscillator 1 is built in an electronic apparatus by mountingthe crystal vibrator A and the IC component (the oscillation circuit andthe temperature compensation circuit) on a main board MB located on theside of an external device (for example, an electronic apparatus such asa cellular phone as shown in FIG. 9 or a GPS module) B.

As a user who has purchased the temperature sensor-attached crystalvibrator Amounts it on the main board MB located inside the externaldevice B, a crystal oscillator is formed in accordance with acombination of the temperature sensor-attached crystal vibrator A andthe oscillation circuit and the temperature compensation circuit (ICcomponent 85) disposed on the main board MB.

The package 2 includes: an insulating container (insulating substrate) 4that is formed from a ceramic having the upper concave portion 3 on theupper face; two internal pads (component mounting pads) 5 that arearranged inside the upper concave portion 3 and are electricallyconnected to excitation electrodes of the crystal vibration device 20; aplurality of mounting terminals 6 that are arranged on the outer bottomface of the insulating container 4; an external pad (temperature sensormounting pad) 12 arranged inside the outer bottom face (a lower concaveportion 11) of the insulating container that is used for mounting thetemperature sensor 80; a connection conductor, which is not shown in thefigure, allowing each mounting terminal 6, each internal pad 5, and theexternal pad 12 to be conductive to one another; a lid member 10 made ofmetal (for example, Kovar) that seals the upper concave portion 3 in anairtight manner in a state in which two internal pads 5 disposed insidethe upper concave portion and two excitation electrodes disposed on thecrystal vibration device (piezoelectric vibration device) 20 areelectrically connected to each other; and a heat transfer member 15 thatconnects the lid member and the temperature sensor 80 so as to beheat-transferable and has thermal conductivity higher than the materialof the insulating substrate that is formed from a ceramic.

The IC component 85 mounted in the external device B includes anoscillation circuit 86, a temperature compensation circuit 87, an A/Dconverter 88, and the like. The output (temperature information) of thetemperature sensor 80 mounted on the crystal vibrator A side is formedas a digital signal by the A/D converter 88, and the digital signal isinput to the temperature compensation circuit 87. The temperaturecompensation circuit 87 outputs frequency control information generatedbased on the temperature information to the oscillation circuit 86. Theoscillation circuit 86 generates temperature compensation frequencyinformation based on the temperature control information and outputs thetemperature compensation frequency information.

According to this embodiment, since the temperature sensor 80 mounted onthe crystal vibrator A side is thermally connected to the lid member 10that is disposed at a position proximal to the crystal vibration device20 through the heat transfer member 15, the sensitivity that is almostthe same as that of a case where the temperature of the crystalvibration device is directly detected by the temperature sensor can beacquired.

In addition, a circuit portion that includes the oscillation circuit 86,a power supply, the temperature compensation circuit 87, and the likethat have heat generating elements such as amplifier circuits can bearranged so as to be located far from the crystal vibration device.Accordingly, the temperature sensor 80 can detect the temperature of thecrystal vibration device more accurately.

Although the configuration has been described in which the neutralterminal is not conductive to the mounting terminal, for example, evenwhen a wiring is connected between the neutral terminal and the mountingterminal, in a case where the heat transfer characteristics are superiorowing to a structure in which there are more short paths on the side ofthe wiring that is a heat transfer member connecting the neutralterminal and the lid member, the advantages according to the embodimentof the invention can be expected. However, in order to acquiresufficient advantages, as in the above-described embodiments, it is morepreferable to employ a configuration in which the neutral terminal isnot allowed to be conductive to the mounting terminal.

Each embodiment of the invention that includes the above-describedconfiguration has the following advantages.

In a crystal oscillator provided with a temperature compensationfunction, when the frequency is corrected based on an incorrecttemperature data signal (voltage value) for the crystal vibration devicethat is detected by the temperature sensor, there is a problem in thatthe frequency drift characteristics, which represent a frequencyvariation difference between an oscillation frequency at a time pointwhen a voltage is applied to the crystal oscillator and an oscillationfrequency at a time point when a predetermined time elapses after theapplication of the voltage, deteriorate.

According to the embodiment of the invention, the lid member that islocated at a position closest to the crystal vibration device housed inan airtight space of the package and the temperature sensor (the ICcomponent in which the temperature sensor is mounted) are thermallyconnected to each other through the heat transfer member having highthermal conductivity. Accordingly, incorrect temperature data is notoutput from the temperature sensor, whereby the frequency driftcharacteristics can be improved.

In addition, in the above-described embodiments, the insulatingcontainer including the upper concave portion 3 on the upper face sidehas been illustrated as the insulating substrate 4 as an example.However, it may be configured such that the crystal vibration device 20is mounted on the insulating substrate 4 having a flat upper face byusing a conductive adhesive, and a space on the insulating substrateincluding the crystal vibration device is sealed by a reversebowl-shaped metal lid (lid member) in an airtight manner.

In the above-described embodiments, as a representative example of thepiezoelectric oscillator, the crystal oscillator has been illustrated.However, the embodiment of the invention can be also applied to ageneral oscillator using a piezoelectric vibration device that is formedfrom a piezoelectric material or a piezoelectric device such as anangular-velocity sensor that uses a piezoelectric vibration device as aphysical amount sensor.

The entire disclosure of Japanese Patent Application No. 2011-054014,filed Mar. 11, 2011 is expressly incorporated by reference herein.

What is claimed is:
 1. A piezoelectric device comprising: apiezoelectric vibration element; a temperature sensor that detectstemperature; an insulating substrate that has a first surface and asecond surface opposite to the first surface, the first surface havingan element mounting pad on which the piezoelectric vibration element ismounted, the second surface having a recess that has a temperaturesensor mounting pad on which the temperature sensor is mounted; a metalsealing body on the first surface of the insulating substrate, the metalsealing body surrounding the piezoelectric vibration element in a planview; a metal lid member that seals the piezoelectric vibration elementbetween the first surface of the insulating substrate and the metal lidmember, the metal lid member being connected to the metal sealing body;a heat transfer metal member including a wire in the insulatingsubstrate, wherein the heat transfer metal member directly extends fromthe temperature sensor mounting pad to the metal sealing body withoutany other intervening pad or terminal so as to thermally connect thetemperature sensor and the metal lid member.
 2. The piezoelectric deviceaccording to claim 1, wherein the temperature sensor is a thermistor. 3.The piezoelectric device according to claim 1, wherein the heat transfermetal member is formed inside the insulating substrate from a boundarybetween the insulating substrate and the temperature sensor mountingpad.
 4. The piezoelectric device according to claim 2, wherein the heattransfer metal member is formed inside the insulating substrate from aboundary between the insulating substrate and the temperature sensormounting pad.
 5. The piezoelectric device according to claim 1, furthercomprising: a mounting terminal that is formed on a ridge of the recess;and a connection conductor that extends from the mounting terminal,wherein the mounting terminal and the temperature sensor mounting padare electrically connected to each other through the connectionconductor.
 6. The piezoelectric device according to claim 2, furthercomprising: a mounting terminal that is formed on a ridge of the recess;and a connection conductor that extends from the mounting terminal,wherein the mounting terminal and the temperature sensor mounting padare electrically connected to each other through the connectionconductor.
 7. The piezoelectric device according to claim 1, wherein theheat transfer metal member includes a plurality of wirings.
 8. Thepiezoelectric device according to claim 2, wherein the heat transfermetal member includes a plurality of wirings.
 9. The piezoelectricdevice according to claim 5, further comprising: another mountingterminal that is formed on the second surface, wherein the elementmounting pad and the another mounting terminal are electricallyconnected to each other.
 10. The piezoelectric device according to claim6, further comprising: another mounting terminal that is formed on thesecond surface, wherein the element mounting pad and the anothermounting terminal are electrically connected to each other.
 11. Thepiezoelectric device according to claim 1, wherein the first surface hasanother recess in which the element mounting pad is formed.
 12. Thepiezoelectric device according to claim 2, wherein the first surface hasanother recess in which the element mounting pad is formed.
 13. Anelectronic apparatus comprising: the piezoelectric device according toclaim
 1. 14. An electronic apparatus comprising: the piezoelectricdevice according to claim
 2. 15. An electronic apparatus comprising: thepiezoelectric device according to claim
 3. 16. An electronic apparatuscomprising: the piezoelectric device according to claim
 4. 17. Anelectronic apparatus comprising: the piezolectric device according toclaim
 5. 18. An electronic apparatus comprising: the piezoelectricdevice according to claim
 6. 19. An electronic apparatus comprising: thepiezoelectric device according to claim
 11. 20. An electronic apparatuscomprising: the piezoelectric device according to claim
 12. 21. Apiezoelectric device comprising: a piezoelectric vibration element; atemperature sensor that detects temperature; an insulating substratethat has a first surface and a second surface opposite to the firstsurface, an element mounting pad, which is formed on the first surface,on which the piezoelectric vibration element is mounted, the secondsurface having a recess that has a temperature sensor mounting pad onwhich the temperature sensor is mounted; a metal sealing body that isformed on the first surface of the insulating substrate so as tosurround the piezoelectric vibration element in a plan view; a metal lidmember that seals the piezoelectric vibration element between the firstsurface of the insulating substrate and the metal lid member, the metallid member being connected to the metal sealing body; a heat transfermetal member including a plurality of wirings in the insulatingsubstrate, wherein the heat transfer metal member extends from thetemperature sensor mounting pad to the metal sealing body so as tothermally connect between the temperature sensor and the metal lidmember.
 22. A piezoelectric device comprising: a piezoelectric vibrationelement; a temperature sensor that detects temperature; an insulatingsubstrate that has a first surface and a second surface opposite to thefirst surface, the first surface having an element mounting pad on whichthe piezoelectric vibration element is mounted, the second surfacehaving a recess that has a temperature sensor mounting pad on which thetemperature sensor is mounted; a metal sealing body on the first surfaceof the insulating substrate, the metal sealing body surrounding thepiezoelectric vibration element in a plan view; a metal lid member thatseals the piezoelectric vibration element between the first surface ofthe insulating substrate and the metal lid member, the metal lid memberbeing connected to the metal sealing body; a heat transfer metal memberincluding a wire in the insulating substrate, wherein the heat transfermetal member extends from the temperature sensor mounting pad to themetal sealing body to define a thermal conductivity pathway between thetemperature sensor mounting pad and the metal sealing body that isentirely embedded in the insulating substrate.